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A collection of homeopathic treatments including preparations made with robinia, castor bean, silver phosphate, and clippings of wintergreen and rosemary. ((Josh Reynolds/Associated Press))

Natural health products are used throughout the country to treat a range of ailments and medical conditions: echinacea for the prevention and suppression of cold symptoms, ginseng as a stimulant and St. John's wort for the treatment of depression, to name just a few.

According to a 2005 Ipsos Reid report, 71 per cent of Canadians use these forms of alternative medicine. Health Canada says $4.3 billion was spent on natural health products in 2004.

What are natural health products?

Natural health products comprise an assortment of substances including vitamins and minerals, herbal remedies and teas, homeopathic medicines and probiotics. They are made from a range of materials: plants, including bark and roots, algae, fungus, or non-human animal materials such as elk antler or shark cartilage.

How are they regulated?

On Jan. 1, 2004, the Natural Health Products Regulations came into effect, the first attempt at policing the industry. It grants licences in the form of a Natural Product Number to natural health products approved for sale in the country.

Prior to this, they were identified as either food or drugs but as alternative forms of medicine became more popular, the government created the special designation. Natural health products are now considered a subset of drugs under the Food and Drug Act.

Health Canada says it ensures that natural health products are safe, effective and of high quality before granting a licence. The government has a website, which includes a list of permitted substances and general information on natural health products.

What should I look for?

All approved products must contain specific information on their principal display panels, including product name, dosage amount and the eight-digit NPN issued by the government.

"The labels have a lot more information then they used to and I think people need to stop and take some time to read the label," says Heather Boon, associate professor at the University of Toronto' s Leslie Dan faculty of pharmacy.

The package should also include the name and quantity of each medicinal ingredient, recommended use and duration, expiry date and risk information, says Boon, who was the chair of Heath Canada's expert advisory committee on natural health products before it was disbanded in late 2009.

All natural health products previously identified as drugs, and given their own drug identification number, or DIN, were to be reassigned a NPN according to the 2004 regulations.

However, some products have not been assigned a NPN because they have not yet completed the licensing process. They continue to be sold under an exemption number, or EN, after passing an initial assessment to ensure their safety, quality and efficacy.

What about homeopathic medicines?

Health Canada treats homeopathic medicines — which are made by extremely diluting substances that are said to have effects similar to the condition being treated — differently because they can contain materials restricted in other natural health products.

These products have their own homeopathic medicine numbers, or DIN-HMs, which are also assigned after receiving regulatory approval.

These products require a label that includes one of the following phrases: "homeopathic medicine," "homeopathic remedy," "homeopathic drug," or "homeopathic preparation." The government says the special designation number and label makes it easier for consumers to identify the products.

What are the testing procedures?

Prior to being assigned a licence, all natural health products producers must present evidence of safety and efficacy during a pre-market review. Boon says the process is similar to the testing procedures for pharmaceutical drugs.

The type of claim being made ultimately influences how much evidence needs to be submitted, she says.

The strongest evidence comes from randomized, controlled and preferably blinded, clinical trials, Health Canada says. In most cases, a minimum of two clinical trials are required to demonstrate preventive medical claims, it says.

"If the claim the company wants to make is this cures your headache, then yes, we need to see double-blind, clinical trials," Boon says.

There is also a category for traditional claims, where companies need to submit evidence that a product has been used by a branch of traditional medicine to treat a particular condition consecutively for 50 years, she says, adding they do not have to submit clinical data.

These kinds of natural health products also need to include a reference to the traditional nature of their claims.

Preventive claims — where a product says it will stop a person from getting a cold for instance — are not amenable to clinical trials because it is difficult to establish the cause of why something did not happen, Boon says.

Accordingly, preventive claims are usually tested with cohort studies, where a group of people is studied over a long period of time to test for the incidence, or absence, of a particular medical condition.

The language on the bottle is the best indication of the medical claims of the natural health product, Boon says. If it says it "may prevent" a condition, chances are the scientific evidence is not quite there, she says.

Studies should also be of a sufficient length to ensure that the consumption of a natural health product does not pose a long-term health risk. Health Canada says it also checks to see if there are possible adverse effects when the substance is taken in conjunction with other natural health products, prescription drugs or foods.

Are there any claims that cannot be made?

"It's based on the evidence," Boon says. "If you have good scientific evidence you can make pretty much make any claim you want."

However, she says there are some claims that are not amenable to over-the-counter treatments, including serious conditions, such as cancer, where a person cannot self-diagnose the condition and cannot verify whether the treatment is working.

Where are they sold?

Natural health products must be considered safe for over-the-counter sale as they do not require a prescription and can be purchased at a number of stores, including supermarkets, pharmacies and health stores.

The government says the intent of the regulations was to give consumers the option to choose products without having to consult a health-care provider.

What should I consider before taking natural health products?

A Health Canada document warns that many people assume all natural health products are safe because they are labeled "natural." However, it says any substance designed to affect the body has the potential to cause health problems, adding that children, pregnant or breastfeeding women, seniors and those diagnosed with a serious illness should be particularly cautious.

The document includes a list of possible side-effects or risks to consider: taking a natural health product for a self-diagnosed condition that could be a serious medical condition prompting a delay in supervised treatment, possible interaction with prescription drugs or over-the-counter medicines and allergic reactions.

Consumers should read all product information before starting treatment. Health Canada says consumers should speak with a health-care professional, such as a medical doctor, nurse, pharmacist or naturopathic doctor, if they have any further questions about natural health products.

"They need to consider that these things are drugs," Boon says. "They're taking them for medicinal purposes and so they need to treat them with respect."